This invention relates to a process for the microbial degradation of dichloro-diphenyl-trichloroethane (hereinafter referred to as DDT). More particularly, it relates to a method for degrading DDT by means of microorganisms in order to clean up and eliminate this pollutant as it may occur in the open sea, inland fresh waters, tidal pools, harbors and the like, industrial effluent discharges, sewage and other pipeline systems, farm soil or other land areas including industrial sites, etc. The invention is applicable not only for cleaning up DDT as a contaminant or pollutant in open environmental systems, but also in closed systems as, for example, in industrial, commercial or government plants and installations and in various laboratory operations.
Environmental cleanup is of much concern to the country and to the world today. DDT is a chemical that was widely used as an effective insecticide and pesticide; however, its use has been banned in many jurisdictions because of its potential hazard to human health. Hence, it would be extremely desirable to be able to use this substance safely and effectively without the danger of contamination. The present invention makes it possible to degrade DDT microbially so that its use is again made possible.
DDT is a very persistent substance and is extremely difficult to degrade once it is present in the environment. Residues of DDT have been noted in fish, birds and mammals, which include those used for human food as well as the wild animals. Although the data are incomplete at the present time, there is significant evidence that most humans have some residues of DDT in their tissues. The effect on humans of such residues is also unclear at the present time, but some evidence indicates very severe and harmful effects from DDT poisoning. As with many other chlorinated hydrocarbons, such as PCBs, even small dosages of DDT can be toxic. In any event, the presence of DDT in the environment has been a great concern to scientists and other people concerned with health, safety and welfare, and there has been a great need for the development of a procedure for the degradation of such substances.
Accordingly, one of the objects of the present invention is to provide a method for degrading DDT wherever it may appear as a contaminant or pollutant.
Another object of the present invention is to provide a process for the microbial degradation of DDT wherever desired; for example, as a means of cleaning up closed and open waters, industrial effluent discharges, polluted marshlands estuaries, marine environments, disposal lagoons, contaminated industrial areas, soils and farmlands, and in other situations where DDT may become accumulated.
A further object of the invention is to provide a procedure for degrading DDT readily, efficiently, and relatively economically.
A still further object of the invention is to provide microorganisms that are capable of degrading DDT, leaving a detoxified and beneficial cell mass, these microorganisms being completely nonpathogenic to marine fauna and flora, humans and animals.
Yet another object of the invention is to provide a method for the degradation of DDT wherein there is no need for the handling, transporting and storage of heavy, bulky equipment.
These and other objects and advantages of the present invention will become apparent to those skilled in the art from a consideration of the following specification and claims.